Examples of technologies to estimate a self-position which is the current position of a movable body include a technology having a configuration described in JP-A-2008-250906. In the technology described in JP-A-2008-250906, environmental information on surroundings present in a predefined region relative to a movable body is limited, and the limited environmental information is compared with an environmental map held in advance to estimate a self-position.
JP-A-2008-250906 In the configuration of JP-A-2008-250906 described above, however, for example, in a case in which the movable body is a vehicle, the position in the forward-backward direction of the movable body traveling on a straight path is estimated by a method in which the distance and direction of movement of the movable body are determined as functions of the rotation angles and rotational angular velocities of right and left wheels (odometry).
Since environmental information on a straight path is more than environmental information on a curved path immediately after an entry from the straight path into the curved path, the accuracy of estimation of a position in a forward-backward direction is deteriorated until environmental information on the curved path is accumulated in technologies to estimate a self-position by such odometry. Therefore, a problem may occur in that the accuracy of estimation of the self-position is deteriorated when the self-position is estimated on the curved path into which the entry is made from the straight path in the technologies to estimate the self-position by the odometry.